/*

 * jdmaster.c

 *

 * Copyright (C) 1991-1995, Thomas G. Lane.

 * This file is part of the Independent JPEG Group's software.

 * For conditions of distribution and use, see the accompanying README file.

 *

 * This file contains master control logic for the JPEG decompressor.

 * These routines are concerned with selecting the modules to be executed

 * and with determining the number of passes and the work to be done in each

 * pass.

 */



#define JPEG_INTERNALS

#include "jinclude.h"

#include "jpeglib.h"





/* Private state */



typedef struct {

  struct jpeg_decomp_master pub; /* public fields */



  int pass_number;		/* # of passes completed */



  boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */



  /* Saved references to initialized quantizer modules,

   * in case we need to switch modes.

   */

  struct jpeg_color_quantizer * quantizer_1pass;

  struct jpeg_color_quantizer * quantizer_2pass;

} my_decomp_master;



typedef my_decomp_master * my_master_ptr;





/*

 * Determine whether merged upsample/color conversion should be used.

 * CRUCIAL: this must match the actual capabilities of jdmerge.c!

 */



LOCAL boolean

use_merged_upsample (j_decompress_ptr cinfo)

{

#ifdef UPSAMPLE_MERGING_SUPPORTED

  /* Merging is the equivalent of plain box-filter upsampling */

  if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)

    return FALSE;

  /* jdmerge.c only supports YCC=>RGB color conversion */

  if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||

      cinfo->out_color_space != JCS_RGB ||

      cinfo->out_color_components != RGB_PIXELSIZE)

    return FALSE;

  /* and it only handles 2h1v or 2h2v sampling ratios */

  if (cinfo->comp_info[0].h_samp_factor != 2 ||

      cinfo->comp_info[1].h_samp_factor != 1 ||

      cinfo->comp_info[2].h_samp_factor != 1 ||

      cinfo->comp_info[0].v_samp_factor >  2 ||

      cinfo->comp_info[1].v_samp_factor != 1 ||

      cinfo->comp_info[2].v_samp_factor != 1)

    return FALSE;

  /* furthermore, it doesn't work if we've scaled the IDCTs differently */

  if (cinfo->comp_info[0].DCT_scaled_size != cinfo->min_DCT_scaled_size ||

      cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size ||

      cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_scaled_size)

    return FALSE;

  /* ??? also need to test for upsample-time rescaling, when & if supported */

  return TRUE;			/* by golly, it'll work... */

#else

  return FALSE;

#endif

}





/*

 * Compute output image dimensions and related values.

 * NOTE: this is exported for possible use by application.

 * Hence it mustn't do anything that can't be done twice.

 * Also note that it may be called before the master module is initialized!

 */



GLOBAL void

jpeg_calc_output_dimensions (j_decompress_ptr cinfo)

/* Do computations that are needed before master selection phase */

{

  int ci;

  jpeg_component_info *compptr;



  /* Prevent application from calling me at wrong times */

  if (cinfo->global_state != DSTATE_READY)

    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);



#ifdef IDCT_SCALING_SUPPORTED



  /* Compute actual output image dimensions and DCT scaling choices. */

  if (cinfo->scale_num * 8 <= cinfo->scale_denom) {

    /* Provide 1/8 scaling */

    cinfo->output_width = (JDIMENSION)

      jdiv_round_up((long) cinfo->image_width, 8L);

    cinfo->output_height = (JDIMENSION)

      jdiv_round_up((long) cinfo->image_height, 8L);

    cinfo->min_DCT_scaled_size = 1;

  } else if (cinfo->scale_num * 4 <= cinfo->scale_denom) {

    /* Provide 1/4 scaling */

    cinfo->output_width = (JDIMENSION)

      jdiv_round_up((long) cinfo->image_width, 4L);

    cinfo->output_height = (JDIMENSION)

      jdiv_round_up((long) cinfo->image_height, 4L);

    cinfo->min_DCT_scaled_size = 2;

  } else if (cinfo->scale_num * 2 <= cinfo->scale_denom) {

    /* Provide 1/2 scaling */

    cinfo->output_width = (JDIMENSION)

      jdiv_round_up((long) cinfo->image_width, 2L);

    cinfo->output_height = (JDIMENSION)

      jdiv_round_up((long) cinfo->image_height, 2L);

    cinfo->min_DCT_scaled_size = 4;

  } else {

    /* Provide 1/1 scaling */

    cinfo->output_width = cinfo->image_width;

    cinfo->output_height = cinfo->image_height;

    cinfo->min_DCT_scaled_size = DCTSIZE;

  }

  /* In selecting the actual DCT scaling for each component, we try to

   * scale up the chroma components via IDCT scaling rather than upsampling.

   * This saves time if the upsampler gets to use 1:1 scaling.

   * Note this code assumes that the supported DCT scalings are powers of 2.

   */

  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

       ci++, compptr++) {

    int ssize = cinfo->min_DCT_scaled_size;

    while (ssize < DCTSIZE &&

	   (compptr->h_samp_factor * ssize * 2 <=

	    cinfo->max_h_samp_factor * cinfo->min_DCT_scaled_size) &&

	   (compptr->v_samp_factor * ssize * 2 <=

	    cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size)) {

      ssize = ssize * 2;

    }

    compptr->DCT_scaled_size = ssize;

  }



  /* Recompute downsampled dimensions of components;

   * application needs to know these if using raw downsampled data.

   */

  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

       ci++, compptr++) {

    /* Size in samples, after IDCT scaling */

    compptr->downsampled_width = (JDIMENSION)

      jdiv_round_up((long) cinfo->image_width *

		    (long) (compptr->h_samp_factor * compptr->DCT_scaled_size),

		    (long) (cinfo->max_h_samp_factor * DCTSIZE));

    compptr->downsampled_height = (JDIMENSION)

      jdiv_round_up((long) cinfo->image_height *

		    (long) (compptr->v_samp_factor * compptr->DCT_scaled_size),

		    (long) (cinfo->max_v_samp_factor * DCTSIZE));

  }



#else /* !IDCT_SCALING_SUPPORTED */



  /* Hardwire it to "no scaling" */

  cinfo->output_width = cinfo->image_width;

  cinfo->output_height = cinfo->image_height;

  /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,

   * and has computed unscaled downsampled_width and downsampled_height.

   */



#endif /* IDCT_SCALING_SUPPORTED */



  /* Report number of components in selected colorspace. */

  /* Probably this should be in the color conversion module... */

  switch (cinfo->out_color_space) {

  case JCS_GRAYSCALE:

    cinfo->out_color_components = 1;

    break;

  case JCS_RGB:

#if RGB_PIXELSIZE != 3

    cinfo->out_color_components = RGB_PIXELSIZE;

    break;

#endif /* else share code with YCbCr */

  case JCS_YCbCr:

    cinfo->out_color_components = 3;

    break;

  case JCS_CMYK:

  case JCS_YCCK:

    cinfo->out_color_components = 4;

    break;

  default:			/* else must be same colorspace as in file */

    cinfo->out_color_components = cinfo->num_components;

    break;

  }

  cinfo->output_components = (cinfo->quantize_colors ? 1 :

			      cinfo->out_color_components);



  /* See if upsampler will want to emit more than one row at a time */

  if (use_merged_upsample(cinfo))

    cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;

  else

    cinfo->rec_outbuf_height = 1;

}





/*

 * Several decompression processes need to range-limit values to the range

 * 0..MAXJSAMPLE; the input value may fall somewhat outside this range

 * due to noise introduced by quantization, roundoff error, etc.  These

 * processes are inner loops and need to be as fast as possible.  On most

 * machines, particularly CPUs with pipelines or instruction prefetch,

 * a (subscript-check-less) C table lookup

 *		x = sample_range_limit[x];

 * is faster than explicit tests

 *		if (x < 0)  x = 0;

 *		else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;

 * These processes all use a common table prepared by the routine below.

 *

 * For most steps we can mathematically guarantee that the initial value

 * of x is within MAXJSAMPLE+1 of the legal range, so a table running from

 * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial

 * limiting step (just after the IDCT), a wildly out-of-range value is 

 * possible if the input data is corrupt.  To avoid any chance of indexing

 * off the end of memory and getting a bad-pointer trap, we perform the

 * post-IDCT limiting thus:

 *		x = range_limit[x & MASK];

 * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit

 * samples.  Under normal circumstances this is more than enough range and

 * a correct output will be generated; with bogus input data the mask will

 * cause wraparound, and we will safely generate a bogus-but-in-range output.

 * For the post-IDCT step, we want to convert the data from signed to unsigned

 * representation by adding CENTERJSAMPLE at the same time that we limit it.

 * So the post-IDCT limiting table ends up looking like this:

 *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,

 *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),

 *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),

 *   0,1,...,CENTERJSAMPLE-1

 * Negative inputs select values from the upper half of the table after

 * masking.

 *

 * We can save some space by overlapping the start of the post-IDCT table

 * with the simpler range limiting table.  The post-IDCT table begins at

 * sample_range_limit + CENTERJSAMPLE.

 *

 * Note that the table is allocated in near data space on PCs; it's small

 * enough and used often enough to justify this.

 */



LOCAL void

prepare_range_limit_table (j_decompress_ptr cinfo)

/* Allocate and fill in the sample_range_limit table */

{

  JSAMPLE * table;

  int i;



  table = (JSAMPLE *)

    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

		(5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));

  table += (MAXJSAMPLE+1);	/* allow negative subscripts of simple table */

  cinfo->sample_range_limit = table;

  /* First segment of "simple" table: limit[x] = 0 for x < 0 */

  MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));

  /* Main part of "simple" table: limit[x] = x */

  for (i = 0; i <= MAXJSAMPLE; i++)

    table[i] = (JSAMPLE) i;

  table += CENTERJSAMPLE;	/* Point to where post-IDCT table starts */

  /* End of simple table, rest of first half of post-IDCT table */

  for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)

    table[i] = MAXJSAMPLE;

  /* Second half of post-IDCT table */

  MEMZERO(table + (2 * (MAXJSAMPLE+1)),

	  (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));

  MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),

	  cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));

}





/*

 * Master selection of decompression modules.

 * This is done once at jpeg_start_decompress time.  We determine

 * which modules will be used and give them appropriate initialization calls.

 * We also initialize the decompressor input side to begin consuming data.

 *

 * Since jpeg_read_header has finished, we know what is in the SOF

 * and (first) SOS markers.  We also have all the application parameter

 * settings.

 */



LOCAL void

master_selection (j_decompress_ptr cinfo)

{

  my_master_ptr master = (my_master_ptr) cinfo->master;

  boolean use_c_buffer;

  long samplesperrow;

  JDIMENSION jd_samplesperrow;



  /* Initialize dimensions and other stuff */

  jpeg_calc_output_dimensions(cinfo);

  prepare_range_limit_table(cinfo);



  /* Width of an output scanline must be representable as JDIMENSION. */

  samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;

  jd_samplesperrow = (JDIMENSION) samplesperrow;

  if ((long) jd_samplesperrow != samplesperrow)

    ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);



  /* Initialize my private state */

  master->pass_number = 0;

  master->using_merged_upsample = use_merged_upsample(cinfo);



  /* Color quantizer selection */

  master->quantizer_1pass = NULL;

  master->quantizer_2pass = NULL;

  /* No mode changes if not using buffered-image mode. */

  if (! cinfo->quantize_colors || ! cinfo->buffered_image) {

    cinfo->enable_1pass_quant = FALSE;

    cinfo->enable_external_quant = FALSE;

    cinfo->enable_2pass_quant = FALSE;

  }

  if (cinfo->quantize_colors) {

    if (cinfo->raw_data_out)

      ERREXIT(cinfo, JERR_NOTIMPL);

    /* 2-pass quantizer only works in 3-component color space. */

    if (cinfo->out_color_components != 3) {

      cinfo->enable_1pass_quant = TRUE;

      cinfo->enable_external_quant = FALSE;

      cinfo->enable_2pass_quant = FALSE;

      cinfo->colormap = NULL;

    } else if (cinfo->colormap != NULL) {

      cinfo->enable_external_quant = TRUE;

    } else if (cinfo->two_pass_quantize) {

      cinfo->enable_2pass_quant = TRUE;

    } else {

      cinfo->enable_1pass_quant = TRUE;

    }



    if (cinfo->enable_1pass_quant) {

#ifdef QUANT_1PASS_SUPPORTED

      jinit_1pass_quantizer(cinfo);

      master->quantizer_1pass = cinfo->cquantize;

#else

      ERREXIT(cinfo, JERR_NOT_COMPILED);

#endif

    }



    /* We use the 2-pass code to map to external colormaps. */

    if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {

#ifdef QUANT_2PASS_SUPPORTED

      jinit_2pass_quantizer(cinfo);

      master->quantizer_2pass = cinfo->cquantize;

#else

      ERREXIT(cinfo, JERR_NOT_COMPILED);

#endif

    }

    /* If both quantizers are initialized, the 2-pass one is left active;

     * this is necessary for starting with quantization to an external map.

     */

  }



  /* Post-processing: in particular, color conversion first */

  if (! cinfo->raw_data_out) {

    if (master->using_merged_upsample) {

#ifdef UPSAMPLE_MERGING_SUPPORTED

      jinit_merged_upsampler(cinfo); /* does color conversion too */

#else

      ERREXIT(cinfo, JERR_NOT_COMPILED);

#endif

    } else {

      jinit_color_deconverter(cinfo);

      jinit_upsampler(cinfo);

    }

    jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);

  }

  /* Inverse DCT */

  jinit_inverse_dct(cinfo);

  /* Entropy decoding: either Huffman or arithmetic coding. */

  if (cinfo->arith_code) {

    ERREXIT(cinfo, JERR_ARITH_NOTIMPL);

  } else {

    if (cinfo->progressive_mode) {

#ifdef D_PROGRESSIVE_SUPPORTED

      jinit_phuff_decoder(cinfo);

#else

      ERREXIT(cinfo, JERR_NOT_COMPILED);

#endif

    } else

      jinit_huff_decoder(cinfo);

  }



  /* Initialize principal buffer controllers. */

  use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;

  jinit_d_coef_controller(cinfo, use_c_buffer);



  if (! cinfo->raw_data_out)

    jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);



  /* We can now tell the memory manager to allocate virtual arrays. */

  (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);



  /* Initialize input side of decompressor to consume first scan. */

  (*cinfo->inputctl->start_input_pass) (cinfo);



#ifdef D_MULTISCAN_FILES_SUPPORTED

  /* If jpeg_start_decompress will read the whole file, initialize

   * progress monitoring appropriately.  The input step is counted

   * as one pass.

   */

  if (cinfo->progress != NULL && ! cinfo->buffered_image &&

      cinfo->inputctl->has_multiple_scans) {

    int nscans;

    /* Estimate number of scans to set pass_limit. */

    if (cinfo->progressive_mode) {

      /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */

      nscans = 2 + 3 * cinfo->num_components;

    } else {

      /* For a nonprogressive multiscan file, estimate 1 scan per component. */

      nscans = cinfo->num_components;

    }

    cinfo->progress->pass_counter = 0L;

    cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;

    cinfo->progress->completed_passes = 0;

    cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);

    /* Count the input pass as done */

    master->pass_number++;

  }

#endif /* D_MULTISCAN_FILES_SUPPORTED */

}





/*

 * Per-pass setup.

 * This is called at the beginning of each output pass.  We determine which

 * modules will be active during this pass and give them appropriate

 * start_pass calls.  We also set is_dummy_pass to indicate whether this

 * is a "real" output pass or a dummy pass for color quantization.

 * (In the latter case, jdapi.c will crank the pass to completion.)

 */



METHODDEF void

prepare_for_output_pass (j_decompress_ptr cinfo)

{

  my_master_ptr master = (my_master_ptr) cinfo->master;



  if (master->pub.is_dummy_pass) {

#ifdef QUANT_2PASS_SUPPORTED

    /* Final pass of 2-pass quantization */

    master->pub.is_dummy_pass = FALSE;

    (*cinfo->cquantize->start_pass) (cinfo, FALSE);

    (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);

    (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);

#else

    ERREXIT(cinfo, JERR_NOT_COMPILED);

#endif /* QUANT_2PASS_SUPPORTED */

  } else {

    if (cinfo->quantize_colors && cinfo->colormap == NULL) {

      /* Select new quantization method */

      if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {

	cinfo->cquantize = master->quantizer_2pass;

	master->pub.is_dummy_pass = TRUE;

      } else if (cinfo->enable_1pass_quant) {

	cinfo->cquantize = master->quantizer_1pass;

      } else {

	ERREXIT(cinfo, JERR_MODE_CHANGE);

      }

    }

    (*cinfo->idct->start_pass) (cinfo);

    (*cinfo->coef->start_output_pass) (cinfo);

    if (! cinfo->raw_data_out) {

      if (! master->using_merged_upsample)

	(*cinfo->cconvert->start_pass) (cinfo);

      (*cinfo->upsample->start_pass) (cinfo);

      if (cinfo->quantize_colors)

	(*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);

      (*cinfo->post->start_pass) (cinfo,

	    (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));

      (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);

    }

  }



  /* Set up progress monitor's pass info if present */

  if (cinfo->progress != NULL) {

    cinfo->progress->completed_passes = master->pass_number;

    cinfo->progress->total_passes = master->pass_number +

				    (master->pub.is_dummy_pass ? 2 : 1);

    /* In buffered-image mode, we assume one more output pass if EOI not

     * yet reached, but no more passes if EOI has been reached.

     */

    if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {

      cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);

    }

  }

}





/*

 * Finish up at end of an output pass.

 */



METHODDEF void

finish_output_pass (j_decompress_ptr cinfo)

{

  my_master_ptr master = (my_master_ptr) cinfo->master;



  if (cinfo->quantize_colors)

    (*cinfo->cquantize->finish_pass) (cinfo);

  master->pass_number++;

}





#ifdef D_MULTISCAN_FILES_SUPPORTED



/*

 * Switch to a new external colormap between output passes.

 */



GLOBAL void

jpeg_new_colormap (j_decompress_ptr cinfo)

{

  my_master_ptr master = (my_master_ptr) cinfo->master;



  /* Prevent application from calling me at wrong times */

  if (cinfo->global_state != DSTATE_BUFIMAGE)

    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);



  if (cinfo->quantize_colors && cinfo->enable_external_quant &&

      cinfo->colormap != NULL) {

    /* Select 2-pass quantizer for external colormap use */

    cinfo->cquantize = master->quantizer_2pass;

    /* Notify quantizer of colormap change */

    (*cinfo->cquantize->new_color_map) (cinfo);

    master->pub.is_dummy_pass = FALSE; /* just in case */

  } else

    ERREXIT(cinfo, JERR_MODE_CHANGE);

}



#endif /* D_MULTISCAN_FILES_SUPPORTED */





/*

 * Initialize master decompression control and select active modules.

 * This is performed at the start of jpeg_start_decompress.

 */



GLOBAL void

jinit_master_decompress (j_decompress_ptr cinfo)

{

  my_master_ptr master;



  master = (my_master_ptr)

      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

				  SIZEOF(my_decomp_master));

  cinfo->master = (struct jpeg_decomp_master *) master;

  master->pub.prepare_for_output_pass = prepare_for_output_pass;

  master->pub.finish_output_pass = finish_output_pass;



  master->pub.is_dummy_pass = FALSE;



  master_selection(cinfo);

}

